Dispersions are solids particles dispersed in a fluid medium. Emulsions are stable mixtures of two immiscible fluids. Preparing dispersions or emulsions by rapidly passing the materials through passages of unique geometries is known. These methods typically involve subjecting the materials to highly turbulent forces. One particularly effective means includes passing streams of the materials to be mixed through orifices so that the materials impinge upon each other. See e.g. WO96/14925, incorporated herein by reference. Such processes are known to generate substantial heating of the process stream. Thus, heat exchangers have been used before and/or after the mixing process.